Surfactant-based personal care compositions containing cationic water-soluble polyelectrolytes have been found to deliver good conditioning performance to hair and skin substrates. The cationic water-soluble polyelectrolyte polymers can be based on polysaccharide backbones or on synthetic polymer backbones such as acrylamide, methacrylamide, acrylate esters, methacrylate esters, or vinyl pyrrolidone, for example.
Non-cellulosic cationic polysaccharides such as cationic guars, marketed under the trade names N-Hance® or Jaguar® cationic guars, are commonly used as conditioners in products such as shampoos, 2-in-1 or 3-in-1 conditioning shampoos and body washes, laundry detergents, and shampoos to provide conditioning to the hair, conditioning effects to the skin, or to provide conditioning, softening, and antistatic characteristics to fabrics.
Personal care compositions containing cationic oxidized polysaccharides, including cationic oxidized guar compositions, have been found to deliver good conditioning performance to hair and skin substrates, as described in WO2004/091557 and U.S. Pat. No. 7,067,499. The molecular weight of the cationic guar can vary from as low a molecular weight as 10,000 to as high as several million, and have good performance as a conditioning agent. The use of cationic, anionic, amphoteric or hydrophobic acrylamide polymers in conjunction with cationic oxidized polysaccharides such as cationic oxidized guars has been described in WO2004/091557 and U.S. Pat. No. 7,067,499 and in other documents such as WO2006/026750 in combination with cationic guar.
Cationic polyelectrolyte polymers based on synthetic polymers backbones have also found use as conditioning agents and deposition agents in personal care formulations. In U.S. Pat. No. 5,221,530, crosslinked quaternary acrylate/acrylamide copolymers have been disclosed as delivering good wet and dry conditioning and high levels of foam to shampoo and cleansing formulations when used alone and in U.S. Pat. No. 5,417,965, a combination with polyethyleneimine is taught.
In U.S. Pat. No. 5,756,436, non-crosslinked cationic water-soluble polyelectrolytes based on synthetic polymer backbones having charge densities >4 meq/g have been described for use as deposition polymers in conditioning shampoos containing water-insoluble conditioning agents.
In U.S. Pat. No. 6,849,584, non-crosslinked cationic water-soluble polyelectrolytes based on synthetic polymer backbones having a charge density >2 meq/gram have also been described in personal cleansing compositions containing water-insoluble solid particulate materials and phase separation initiators.
In U.S. Pat. No. 6,495,498, a cleansing composition containing combinations of cationic polyelectrolyte polymers has also been described, where one polymer is a cationic polygalactomannan such as cationic guar and another polymer may be a cationic water-soluble synthetic copolymer in the presence of a water-soluble silicone conditioning agent.
In WO2007/065537, an aqueous shampoo composition containing combinations of cationic polymers has also been described, containing dispersed phase droplets of a water insoluble conditioning agent <4 micron in droplet diameter, where one polymer is a cationic polygalactomannan such as cationic guar and another polymer may be a cationic acrylamide copolymer having a charge density <1 meq/gram.
In WO2008/129493, personal cleansing compositions containing combinations of cationic polymers have also been described, where one polymer is a cationic polymer having a charge density <4 meq/g and which forms an isotropic coacervate with the anionic surfactant and the second cationic polymer having a charge density >4 meq/g that forms a lyotropic liquid crystal on combination with the anionic surfactant.
Although these documents demonstrate that cationic polyelectrolyte polymers based on synthetic polymer backbones can deliver conditioning and enhance deposition of silicone and zinc from surfactant-based formulations, the commercial cationic synthetic polyelectrolyte polymers currently available in the marketplace are high in molecular weight, and as a result, impart a “stringy” rheology to surfactant-based formulations. The lower MW cationic synthetic polyelectrolyte polymers that are currently available in the marketplace, have some drawbacks as well such as reduced solubility, reduced clarity and reduced deposition performance in surfactant-based formulas. The cationic, anionic, and nonionic synthetic polyelectrolytes available in the marketplace also contain high levels of residual monomers, such as acrylamide monomer. There is a need to reduce the residual monomer level in these compositions to lower levels.
In addition, the hydrolytic stability of cationic synthetic polyelectrolytes such as cationic (meth) acrylic acid ester polymers is an important aspect of their performance in aqueous formulations. In DE 3544909, cationic synthetic polyelectrolyte polymers derived from poly(meth)acrylic acid esters are susceptible to hydrolysis of the ester functionality in aqueous solutions, with lifetimes ranging from hours to days, at pH values of 6-7.5. In addition, these cationic synthetic polyelectrolyte polymers have high acute aquatic toxicity, depending on their charge density. When the ester function is hydrolyzed, these polymers have much lower ecotoxicity, see Chang et al, “Water Science Technology”, Vol. 44, No. 2-3, 461-468, 2001.
In U.S. Pat. No. 7,375,173, the disclosure of which is hereby incorporated by reference in its entirety, it has been found that cationic synthetic polyelectrolyte terpolymers of improved ecotoxocity can be prepared from polymerization of monomers of (meth)acrylamide, a quaternized (meth)acrylamide derivative, and a (meth)acrylic acid derivative and or hydrolysis stable cationic monomers. This finding is introduced here as reference and is incorporated as part of the disclosure.
Wet and dry measurements are typical test methods used to measure conditioning performance in shampoo and conditioner applications. Commercial conditioning polymers currently available in the marketplace have been reported to reduce the wet combing force experienced on combing wet hair by 30%-80% relative to a shampoo containing no polymer.
Conditioning performance in a shampoo application can also be measured by monitoring the decrease in optical transmittance of a transparent shampoo or cleansing formulation containing conditioning polymers on increasing dilution with water. The larger the drop in transmittance on dilution with water, the greater the level of deposition. The drop in transmittance or decrease in optical clarity of the formulation is associated with precipitation of the conditioning polymer from the shampoo or other cleansing formulation. The conditioning polymer can be deposited in the form of a complex with surfactants in the formulation or in an uncomplexed form.
The amount of silicone, other conditioning oils or functional materials, zinc, or other active or performance material deposited onto hair or the scalp from a shampoo, conditioner, or colorant system, onto skin from a cleansing or conditioning body wash, or onto fabric from a surfactant-based laundry formulation is also a measure of the conditioning or deposition performance of a conditioning or deposition polymer. The uniformity or nonuniformity of deposition of the silicone, other conditioning oils or conditioning materials, zinc, fragrance, or other “active” material can have significant impact on the perceived performance of the cosmetic formulation. The deposition profile is especially important on substrates such as: 1) hair fibers, where deposition along the fiber, from root to tip, is needed to ameliorate the damage in areas toward the tip or end of the hair fiber and to deposit color uniformly from hair coloring formulations and maintain color uniformity along the fibers; 2) on skin, especially in dry or damaged areas of the skin, where deposition of oils, other conditioning agents, active materials such as antimicrobial agents, sunscreen actives, or colorants such as self-tanning ingredients is needed to occur uniformly; and 3) on fabrics, where deposition occurs, especially on damaged or worn areas, of fabrics such as wool, cotton, polyester.
In skincare applications, skin lubricity or reduced friction or softer feel of the skin, reduced water vapor transmission and improved skin elasticity are test methods used to measure skin conditioning. In surfactant-based household cleansing product formulations where conditioning performance is desired, such as dish detergents, laundry detergents, fabric softeners, and antistatic products, conditioning refers to imparting a softer feel to the hands with liquid dish washing soaps or to fabric with laundry detergents or fabric softeners, and eliminating static effects, eliminating fabric fiber breakage or deformation known as pilling. Imparting color retention or color vibrancy properties to fabrics is also important and can be measured.
Although commercial cationic water-soluble synthetic polyelectrolyte polymers have been shown to deliver conditioning and enhance deposition of silicone and zinc from surfactant-based formulations, the commercial water-soluble synthetic polyelectrolyte polymers available in the marketplace are high in molecular weight, and as a result, they impart a stringy rheology to the surfactant-based formulations. Lower MW cationic water-soluble synthetic polyelectrolyte polymers in the marketplace, have some drawbacks such as reduced clarity in surfactant-based formulations, reduced solubility in surfactant-based formulations, and reduced deposition performance in surfactant-based formulations.
Although non-cellulosic cationically modified polysaccharides and cationic water-soluble polyelectrolyte polymers based on synthetic backbones are known to perform as conditioning polymers in surfactant based cleansing formulations and as deposition aids for conditioning oils and active treatment delivery to the hair and skin, the repeated use of these polymers can confer unwanted buildup of conditioning components, such as silicone and other oils, on the hair or skin. This buildup is apparent as an increase in the energy needed to comb through the dry hair, and as a sticky feel to the hair. In addition, these polymers deliver more conditioning to the root end of the hair fiber, and there is a need to create polymer compositions that deliver more uniform deposition of silicone and other actives along the length of the hair fiber, to the middle section and tip of the hair fiber, where the fiber is more damaged and in need of more conditioning. Finally, in the area of antidandruff and delivery of antimicrobial active materials to the scalp, there is a need for increasing the efficiency of delivery of antimicrobial compound from surfactant systems such as shampoos and hand cleansers, as well as better targeting delivery to the scalp and skin, and maintaining it in place for prolonged activity.
There exists a need for improved deposition and deposition profiles of materials such as silicone, fragrance, zinc, and other active materials onto the hair and scalp, from surfactant-based formulations, without undesirable stringiness imparted to the formulation by the surfactants or polymers used in these formulations. There also exists a need for surfactant-based formulations which improve the amount of deposit for oil phases such as silicone, fragrance oils, mineral oil, and particulate materials, such as zinc pyrithione, zinc carbonate, and other active materials, where the lather or foaming property of the composition is maintained or improved.
There is also a need for polymer compositions containing lower levels of residual monomer.